Apparatus and methods for producing and/or providing recirculating optical delay(s)

ABSTRACT

Exemplary apparatus and method can be availed for providing at least one electromagnetic radiation. For example, it is possible to provide at least one first electromagnetic radiation having a frequency that changes over time with a first characteristic period. Further, with at least one hardware arrangement, it is possible to receive and modify the first electromagnetic radiation(s) into at least one second electromagnetic radiation having a frequency that changes over time with a second characteristic period. The second characteristic period can be smaller than the first characteristic period. The hardware arrangement(s) can include a resonant cavity having a round-trip propagation time for the first electromagnetic radiation(s) that can be approximately the same as the first characteristic period.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based upon and claims the benefit of priority fromU.S. Patent Application Ser. No. 61/548,436 filed Oct. 18, 2011, theentire disclosure of which is incorporated herein by reference.

FIELD OF THE DISCLOSURE

Exemplary embodiments of the present disclosure relate to optics, andmore particularly, to apparatus and methods for producing and/orproviding optical delays.

BACKGROUND INFORMATION

Recently, a multiple increase in the repetition rate of swept sourcelasers has been achieved through optical buffering of low duty cycleswept source lasers. In these arrangements, kilometer length andpossibly multiple instances of fiber delay lines are typically utilizedto achieve the appropriate optical buffering. When implementingbuffering schemes greater than 4×, the length and number of fiber delaylines can become tedious to implement and difficult to manage. Sweptsource lasers for OCT imaging have been demonstrated with up to 16×buffer schemes. (See, e.g., Wolfgang Wieser et al., “Multi-MegahertzOCT: High quality 3D imaging at 20 million A-scans and 4.5 GVoxels persecond”, Optics Express, Vol. 18, Issue 14, pp. 14685-14704 (2010)).

Accordingly, there may be a need to address at least some of thedeficiencies described herein above.

OBJECTS AND SUMMARY OF EXEMPLARY EMBODIMENTS

Thus, at least some of the above-described issues and/or deficienciescan be addressed with the exemplary embodiments of the by providingexemplary systems and methods for producing and/or providing opticaldelays.

Accordingly, exemplary apparatus and method can be availed for providingat least one electromagnetic radiation. For example, using at least onefirst hardware arrangement, it is possible to provide at least one firstelectromagnetic radiation having a frequency that changes over time witha first characteristic period. Further, with at least one secondhardware arrangement, it is possible to receive and modify the firstelectromagnetic radiation(s) into at least one second electromagneticradiation having a frequency that changes over time with a secondcharacteristic period. The second characteristic period can be smallerthan the first characteristic period. The hardware arrangement(s) caninclude a resonant cavity having a round-trip propagation time for thefirst electromagnetic radiation(s) that can be approximately the same asthe first characteristic period.

In another exemplary embodiment of the present disclosure, it ispossible, using at least one first hardware arrangement, to provide atleast one first electromagnetic radiation having a frequency thatchanges repetitively over time with a first characteristic duty cycle,where the first characteristic duty cycle is less than 0.5. Further,e.g., using at least one second hardware arrangement, it is possible toreceive and modify the first electromagnetic radiation(s) into at leastone second electromagnetic radiation with a second characteristic dutycycle that is greater than the first characteristic duty cycle. As oneexample, the first characteristic duty cycle can less than ⅓. The secondcharacteristic duty cycle can be approximately 1.

According to a further exemplary embodiment of the present disclosure,the second arrangement(s) can include a coupling device which can beconfigured to admit the first electromagnetic radiation(s), and emit thesecond electromagnetic radiation(s). The coupling device can be an N×Nwaveguide device and/or an acousto-optical modulator. The firstarrangement(s) can include a source arrangement, and the secondarrangement(s) can include a recirculation loop.

In a further exemplary embodiment of the present disclosure, the secondarrangement(s) can further comprise an amplifying device which can beconfigured to amplify the first electromagnetic radiation(s) and/or thesecond electromagnetic radiation(s).

These and other objects, features and advantages of the presentinvention will become apparent upon reading the following detaileddescription of embodiments of the disclosure, when taken in conjunctionwith the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages of the present disclosure willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings showing illustrativeembodiments of the present disclosure, in which:

FIG. 1 is a diagram of an exemplary re-circulating optical bufferingarrangement according to an exemplary embodiment of the presentdisclosure;

FIG. 2 is a diagram of the exemplary re-circulating optical bufferingarrangement according to another exemplary embodiment of the presentdisclosure; and

FIG. 3 is a diagram of the exemplary re-circulating optical bufferingarrangement according to yet another exemplary embodiment of the presentdisclosure.

Throughout the drawings, the same reference numerals and characters, ifany and unless otherwise stated, are used to denote like features,elements, components, or portions of the illustrated embodiments.Moreover, while the subject disclosure will now be described in detailwith reference to the drawings, it is done so in connection with theillustrative embodiments. It is intended that changes and modificationscan be made to the described embodiments without departing from the truescope and spirit of the subject disclosure as defined by the appendedclaims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

According to certain exemplary embodiments of the present disclosure, are-circulating optical buffering arrangement utilizing a single fiberdelay line can be provided. The exemplary re-circulating arrangement caninclude, e.g., an input port allowing light to be injected into therecirculation loop and an output port allowing light to be extracted atthe end of one complete trip inside the loop. According to certainexemplary embodiments of the present disclosure, an N×N coupling devicecan connect the input and output ports to the recirculation loop. Thefiber delay line can be connected to the recirculation input and outputports of the N×N coupling device.

In a particular exemplary embodiment of the present disclosure, theexemplary re-circulating optical buffering arrangement 100 can utilize asingle fiber delay line 102, as shown in FIG. 1. The exemplaryre-circulating optical buffering arrangement 100 of FIG. 1 can utilize a2×2 port 50/50 passive coupler 104 which can be provided to connectinput port(s) 106 and output ports 108 to a recirculation loop 110.According to certain exemplary embodiments of the present disclosure,the light and/or other electro-magnetic radiation injected into theinput port 106 can be simultaneously coupled, for example, withapproximately a 3 dB loss to the output port 108 and the recirculationloop 110. The light and/or other electro-magnetic radiation exiting therecirculation loop 110 can be re-coupled into both the output port 108and the recirculation loop 110 with, for example, an approximateadditional 3 dB loss. In certain exemplary embodiments of the presentdisclosure, a fixed input to output power ratio can be provided that canbe incrementally reduced in amplitude with the fixed delay loop cycle.The total recirculation loop path time delay can be chosen, for example,to be equal to the injected light ‘pulse’ width. The pulse can be animpulse or, for example, in the case of a swept source laser, the timefor a single sweep. This exemplary re-circulating arrangement can ensureand/or facilitate that the beginning of the delayed light ‘pulse’coincides with the end of the non-delayed or previous delayed ‘pulse’.

According to another exemplary embodiment of the present disclosure, anacousto optical modulator (“AOM”) 202—as a dynamically adjustablecoupling device—can be provided in another exemplary re-circulatingoptical buffering arrangement 200 that is shown, for example, in FIG. 2.According to this exemplary embodiment, the light (or otherelectro-magnetic radiation) injected into an input port 204 can have,for example, multiple (e.g., two) possible paths, such as, e.g., (a)when the AOM 202 is off, the light and/or the electro-magnetic radiationcan travel through the AOM 202 with preferably no diffraction, and canenter an output port 206 of the arrangement; and (b) when the AOM 202 isactive, the light and/or the electro-magnetic radiation can travelthrough the AOM 202 with some diffraction efficiency given by the powerapplied to the AOM 202, and the non diffracted light can enter theoutput port 206 of the arrangement while the diffracted light can entera recirculation loop 208. The light and/or the electro-magneticradiation exiting the recirculation loop 208 can also have multiple,(e.g., two) possible paths, such as, e.g., (a) when the AOM 202 is off,the light can travel through the AOM 202 with no diffraction, and canre-enter the recirculation loop 208; and (b) when the AOM 202 is active,the light and/or the electro-magnetic radiation can travel through theAOM 202 with some diffraction efficiency given by the power applied tothe AOM 202, and the non diffracted light can enter the recirculationloop 208 while the diffracted light can enter the output port 206 of theexemplary arrangement 200.

This exemplary re-circulating arrangement 200 according to the presentdisclosure can facilitate a dynamically adjustable and optimized inputto output power ratios for each fixed delay loop. For example, aninitial injection of light and/or the electro-magnetic radiation intothe recirculation arrangement (200) can occur with maximum power appliedto the AOM 202, which can provide the highest diffraction efficiency.This exemplary configuration can facilitate, for example, the majorityof light to be injected into the recirculation loop 208, while thenon-diffracted light can enter the output port 206 and can become thenon-delayed output. The total exemplary re-circulation loop path timedelay can be selected to be equal to (or approximately the same as) theinjected light “pulse” width. Where the pulse could be an impulse or,for example, in the case of a swept source laser, the time for a singlesweep can be used. This exemplary arrangement 200 can facilitate and/orensure that the beginning of the delayed light ‘pulse’ coincides withthe end of the non-delayed or previous delayed ‘pulse’.

The exemplary recirculation components and path can be chosen in such amanner to reduce the insertion loss, e.g., the zero order path of theAOM can be utilized. This can maximize the number of achievable loopsbefore the optical power loss is too great for a post buffer boosterstage.

According to yet another exemplary embodiment of the present disclosure,an AOM 302—as a dynamically adjustable coupling device—can be providedin yet another exemplary re-circulating optical buffering arrangement300 as shown, for example, in FIG. 3. According to this exemplaryembodiment, light and/or the electro-magnetic radiation injected into aninput port 304 can preferably only enter a recirculation loop 308 whenthe AOM 302 is active. When the AOM 302 is not active, the light and/orthe electro-magnetic radiation preferably travel through the AOM 302with no diffraction and do not enter any port. In this exemplaryarrangement, the injected light and/or the electro-magnetic radiationpreferably no longer provide the first non-delayed output. However, thisexemplary configuration can provide the lowest insertion loss for theinput port to recirculation loop when the AOM 302 is active. The lightand/or the electro-magnetic radiation exiting the recirculation loop 308can have multiple (e.g., two) possible paths, such as, e.g., (a) whenthe AOM 302 is off, the light can travel through the AOM 302 with nodiffraction and can re-enter the recirculation loop 308; and (b) whenthe AOM 302 is active, the light can travel through the AOM 302 withsome diffraction efficiency given by the power applied to the AOM 302,and the non diffracted light and/or the electro-magnetic radiation canenter the recirculation loop 308 while the diffracted light can enterthe output port 306 of the exemplary arrangement 300.

This exemplary embodiment of the present disclosure can facilitate adynamically adjustable and optimized input to output power ratios foreach fixed delay loop. For example, an initial injection of light intothe recirculation arrangement 300 can occur with a maximum power appliedto the AOM 302 providing, e.g., the highest diffraction efficiency. Thisexemplary configuration can facilitate a majority of the light and/orthe electro-magnetic radiation to be injected into the recirculationloop 308, while the non-diffracted light and/or the electro-magneticradiation can be lost. The total re-circulation loop path time delay canbe selected to be equal to, or substantially the same as, the injectedlight ‘pulse’ width. Where the pulse could be an impulse or, forexample, in the case of a swept source laser, the time for a singlesweep is provided. This exemplary arrangement 300 can facilitate thatthe beginning of the delayed light ‘pulse’ coincides with the end of theprevious delayed ‘pulse’.

The foregoing merely illustrates the principles of the presentdisclosure. Various modifications and alterations to the describedembodiments will be apparent to those skilled in the art in view of theteachings herein. Indeed, the arrangements, systems and methodsaccording to the exemplary embodiments of the present disclosure can beused with and/or implement any OCT system, OFDI system, SD-OCT system orother imaging systems, and for example with those described inInternational Patent Application PCT/US2004/029148, filed Sep. 8, 2004which published as International Patent Publication No. WO 2005/047813on May 26, 2005, U.S. patent application Ser. No. 11/266,779, filed Nov.2, 2005 which published as U.S. Patent Publication No. 2006/0093276 onMay 4, 2006, and U.S. patent application Ser. No. 10/501,276, filed Jul.9, 2004 which published as U.S. Patent Publication No. 2005/0018201 onJan. 27, 2005, U.S. Patent Publication No. 2002/0122246, published onMay 9, 2002, U.S. Patent Application No. 61/649,546, U.S. patentapplication Ser. No. 11/625,135, and U.S. Patent Application No.61/589,083, the disclosures of which are incorporated by referenceherein in their entireties.

It should be understood that the exemplary procedures described hereincan be stored on any computer accessible medium, including a hard drive,RAM, ROM, removable disks, CD-ROM, memory sticks, etc., and executed bya processing arrangement and/or computing arrangement which can beand/or include a hardware processors, microprocessor, mini, macro,mainframe, etc., including a plurality and/or combination thereof. Inaddition, certain terms used in the present disclosure, including thespecification, drawings and claims thereof, can be used synonymously incertain instances, including, but not limited to, e.g., data andinformation. It should be understood that, while these words, and/orother words that can be synonymous to one another, can be usedsynonymously herein, that there can be instances when such words can beintended to not be used synonymously. Further, to the extent that theprior art knowledge has not been explicitly incorporated by referenceherein above, it can be explicitly incorporated herein in its entirety.

It will thus be appreciated that those skilled in the art will be ableto devise numerous systems, arrangements and methods which, although notexplicitly shown or described herein, embody the principles of thepresent disclosure and are thus within the spirit and scope of thepresent disclosure. Further, various exemplary embodiments describedherein can be interchangeably used with all other exemplary describedembodiments, as should be understood by those having ordinary skill inthe art. In addition, to the extent that the prior art knowledge has notbeen explicitly incorporated by reference herein above, it is explicitlybeing incorporated herein in its entirety. All publications referencedherein above are incorporated herein by reference in their entireties.

What is claimed is:
 1. An apparatus for providing at least oneelectromagnetic radiation, comprising: at least one source firsthardware arrangement which is configured to provide at least one firstelectromagnetic radiation having a frequency that changes repetitivelyover time with a first characteristic duty cycle, wherein the firstcharacteristic duty cycle is less than 0.5; and at least one opticalsystem second hardware arrangement which is configured to receive andmodify the at least one first electromagnetic radiation into at leastone second electromagnetic radiation with a second characteristic dutycycle that is greater than the first characteristic duty cycle, whereinthe second electromagnetic radiation has a frequency that changesrepetitively over time with a particular period, and wherein the atleast one second arrangement includes a resonant cavity having around-trip propagation time for the at least one first electromagneticradiation that is approximately the same as the particular period. 2.The apparatus according to claim 1, wherein the first characteristicduty cycle is less than ⅓.
 3. The apparatus according to claim 1,wherein the second characteristic duty cycle is approximately
 1. 4. Theapparatus according to claim 1, wherein the at least one secondarrangement includes a coupling device which is configured to admit theat least one first electromagnetic radiation, and emit the at least onesecond electromagnetic radiation.
 5. The apparatus according to claim 4,wherein the coupling device is an N×N waveguide device.
 6. The apparatusaccording to claim 4, wherein the coupling device is an acousto-opticalmodulator.
 7. The apparatus according to claim 1, wherein the at leastone second arrangement includes a recirculation loop.
 8. The apparatusaccording to claim 1, wherein the at least one second arrangementfurther comprising an amplifying device which is configured to amplifyat least one of the at least one first electromagnetic radiation or theat least one second electromagnetic radiation.
 9. A method for providingat least one electromagnetic radiation, comprising: providing at leastone first electromagnetic radiation having a frequency that changesrepetitively over time with a first characteristic duty cycle, whereinthe first characteristic duty cycle is less than 0.5; and with anoptical arrangement, receiving and modifying the at least one firstelectromagnetic radiation into at least one second electromagneticradiation with a second characteristic duty cycle that is greater thanthe first characteristic duty cycle, wherein the second electromagneticradiation has a frequency that changes repetitively over time with aparticular period, and wherein the optical arrangement includes aresonant cavity having a round-trip propagation time for the at leastone first electromagnetic radiation that is approximately the same asthe particular period.